47 lines
1.4 KiB
Plaintext
47 lines
1.4 KiB
Plaintext
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Eager Cursors
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-------------
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With a typical MongoDB cursor, it stays open during iteration and fetches
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batches of documents as you iterate over the cursor. This isn't bad,
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but sometimes you want to fetch all of the data eagerly. For example
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when dealing with web applications, and you want to only show 50
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documents from a collection you should fetch all the data in your
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controller first before going on to the view.
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Benefits:
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- The cursor stays open for a much shorter period of time.
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- Data retrieval and hydration are consolidated operations.
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- Doctrine has the ability to retry the cursor when exceptions during interaction with mongodb are encountered.
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Example:
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.. code-block:: php
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<?php
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$qb = $dm->createQueryBuilder('User')
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->eagerCursor(true);
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$query = $qb->getQuery();
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$users = $query->execute(); // returns instance of Doctrine\MongoDB\ODM\EagerCursor
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At this point all data is loaded from the database and cursors to MongoDB
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have been closed but hydration of the data in to objects has not begun. Once
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insertion starts the data will be hydrated in to PHP objects.
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Example:
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.. code-block:: php
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<?php
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foreach ($users as $user) {
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echo $user->getUsername()."\n";
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}
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Not all documents are converted to objects at once, the hydration is still done
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one document at a time during iteration. The only change is that all data is retrieved
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first.
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